1. Field of the Invention
This invention relates generally to catheters for placement of a therapeutic device at a bifurcation of a body lumen, and more particularly concerns a catheter adapted to utilize two guide wires for precise placement of a therapeutic device with respect to the ostium of a vascular bifurcation for repairing lesions at the vascular bifurcation.
2. Description of Related Art
Stents are typically implanted within a vessel in a contracted state and expanded when in place in the vessel in order to maintain patency of the vessel to allow fluid flow through the vessel. Implantation of such stents is commonly accomplished by mounting the stent on the balloon portion of a catheter, positioning the stent in a body lumen, and expanding the stent to an expanded state by inflation of a balloon within the stent. The stent can then be left in place by deflating the balloon and removing the catheter. An alternate approach is to utilize a self-expanding stent that is introduced in a collapsed state, so that when properly positioned, a retaining sheath can be withdrawn, allowing the stent to expand into position.
A bifurcated stenosis typically can occur in the carotid or coronary arteries at the carina between adjoining arterial branches and around the ostia of the adjoining arterial branches. A bifurcated stenosis can also occur in other bifurcated body lumens, such as in the renal and iliac arteries, for example. Particularly at a vascular bifurcation, lesions may form along the side walls of the blood vessel and at the carina of the bifurcation, contributing to stenosis of the main branch and side branch of the bifurcation, interfering with the normal rheology of flow at the bifurcation, and contributing to the formation of thrombosis.
The accurate, precise delivery of stents at a treatment site of a bifurcated blood vessel has heretofore presented numerous problems. Current methods of placing a stent rely heavily on fluoroscopic equipment and the physician""s ability to accurately visualize and place a stent. This technique is relatively effective in a straight or non-branched anatomy. However, it has been found that the precise positioning of a stent in a specific location such as at the carina of a vascular bifurcation using two dimensional images of a three dimensional vascular bifurcation can pose significant problems for the practitioner. While visualizing the delivery system itself is not a critical issue, holding and accurately placing a stent within 1 mm of an ostium of a side branch vessel at a vascular bifurcation can be a tremendous challenge.
In one method for delivery of a stent at a treatment site of a bifurcated blood vessel, a main vessel stent is implanted at the bifurcation across a side branch, and the structure of main vessel stent must be spread apart sufficiently to form an opening to the side branch vessel for a catheter with a stent for the side branch to be delivered through the opening. The portion of the structure of the main vessel stent to be spread apart is typically selected by trial and error by crossing and recrossing the structure of the main vessel stent with a wire. In addition, the aperture created through the main vessel stent may not provide a clear opening and can create a major distortion in the surrounding structure of the stent.
A need continues to exist for a system for accurately and precisely placing a stent within a side branch portion of a bifurcated blood vessel at the ostium of the side branch vessel to be treated, to minimize the unstented portion of a lesion at the vascular bifurcation, without blocking flow to an unstented side branch of the bifurcation of the blood vessel to be treated. The present invention solves these and other problems, as will be shown.
Briefly, and in general terms, the present invention provides for an ostial placement catheter assembly and a method for placing a therapeutic device with the catheter assembly, permitting improved accuracy and decreased variability in positioning of a therapeutic device such as a graft or stent at an ostium of a bifurcation of a body lumen, by providing a mechanical stop, allowing the graft or stent to be automatically positioned at the ostium of the bifurcation. The ostial placement catheter assembly and method of the invention can also reduce the amount of time needed to place the stent. While the invention can be used in treatment of vascular bifurcations such as can occur in the carotid or coronary arteries, the invention can also be used in treatment of other vascular bifurcations such as at the renal or iliac arteries, for example, or in treatment of other bifurcated body lumens.
The invention accordingly provides for a catheter assembly for placement of a therapeutic device for treatment of a patient""s bifurcated body lumen, such as a bifurcated blood vessel, having a main vessel portion, a plurality of branch vessels extending from the main vessel portion, and a vessel carina between the branch vessels. The catheter assembly includes a placement catheter, with an expandable member mounted adjacent to the distal end of the placement catheter. The placement catheter includes means for inflating and deflating the expandable member, for delivery of a therapeutic device mounted onto the expandable member in one of the branch vessels. The catheter assembly typically includes an adapter hub which provides access to an inflation/deflation lumen. A tracking guide wire lumen within at least a portion of the placement catheter is adapted to receive a tracking guide wire for slidable movement within the tracking guide wire lumen, and a positioning guide member lumen within at least a portion of the placement catheter, having an exit port in the catheter proximal to the expandable member, is adapted to receive a positioning guide member for slidable movement within the positioning guide member lumen.
The present invention also provides for a method for placement of a therapeutic device for treatment of a patient""s bifurcated body lumen, such as a bifurcated vessel, having a main vessel portion, a plurality of branch vessels extending from the main vessel portion, and a vessel carina between the branch vessels. The method involves the steps of providing a placement catheter of the first preferred embodiment, and mounting a therapeutic device on the expandable member for placement in a target branch vessel. The distal end of a tracking guide wire is placed into the target branch vessel, the placement catheter is introduced over the tracking guide wire through the tracking guide wire lumen, and a positioning guide member is introduced into the positioning guide member lumen from the proximal end of the catheter. The positioning guide member remains hidden inside the positioning guide member lumen during tracking of the target vessel. Near the target vessel, the distal end of the positioning guide member is extended through the exit port in the catheter proximal to or proximally adjacent to the expandable member, and is placed in another branch vessel. The placement catheter is then advanced distally in the main vessel until the positioning guide member engages the vessel carina between the branch vessels, and the therapeutic device is placed in the target branch vessel, as is illustrated in FIG. 2.
In a second presently preferred embodiment, the invention provides for a catheter assembly for placement of a therapeutic device for treatment of a patient""s bifurcated body lumen, such as a bifurcated blood vessel, having a main vessel portion, a plurality of branch vessels extending from the main vessel portion, and a vessel carina between the branch vessels. The catheter assembly includes a placement catheter, with an expandable member mounted to the distal end of the placement catheter, and means for inflating and deflating the expandable member. The catheter assembly typically includes an adapter hub which provides access to an inflation/deflation lumen. The expandable member is adapted for mounting and delivery of a therapeutic device in one of the branch vessels. A tracking guide wire lumen within at least a portion of the placement catheter is adapted to receive a tracking guide wire for slidable movement within the tracking guide wire lumen, and a positioning guide member lumen within at least a portion of the placement catheter, and having an exit port in the catheter proximal to the expandable member, is adapted to receive a positioning guide member for slidable movement within the positioning guide member lumen.
The second embodiment of the catheter assembly includes a secondary catheter member mounted to the placement catheter and including a positioning guide member lumen connected in communication with the positioning guide member lumen of the placement catheter, with the positioning guide member lumen of the secondary catheter member adapted to receive the positioning guide member for slidable movement within the positioning guide member lumen of the secondary catheter member. An elongated angle member is mounted to the secondary catheter member, and is adapted to extend between and to be retained by the therapeutic device mounted to the expandable member, between the therapeutic device and the expandable member, so as to form an arch in the elongated angle member between the ends of the elongated angle member and proximal to the therapeutic device. In one currently preferred aspect, one end of the elongated angle member is mounted adjacent to the distal end of the secondary catheter member, and the other end of the elongated angle member is mounted to the placement catheter distal to the expandable member. In another presently preferred aspect means are provided for coupling and uncoupling the distal end of the secondary catheter member to the distal end of the placement catheter distal to the expandable member, and in a currently preferred embodiment the means for coupling and uncoupling includes an annular coupling member connected to the distal end of the placement catheter and adapted to receive the distal end of the positioning guide member.
In the method of placement of a therapeutic device utilizing the catheter assembly of the second preferred embodiment, the distal end of a tracking guide wire is placed into the target branch vessel, and is positioned at a treatment site using standard techniques. The placement catheter is introduced over the tracking guide wire through the tracking guide wire lumen. In a preferred embodiment, an elongated guide member, such as the positioning guide member or another elongated guide member such as a standard guide wire or other type of elongated member, passes through an annular coupling member connected to the distal end of the placement catheter thereby coupling them together. Once the tracking guide wire and elongated guide member are correctly positioned, the catheter is advanced to the treatment site over the tracking wire. The distal end of the secondary catheter member is uncoupled from the distal end of the placement catheter. The positioning guide member is positioned in the alternate, non-treated leg of the bifurcation, and the catheter is advanced over both the tracking guide wire and the positioning guide member until the elongated angle member engages the vessel carina between the branch vessels. The therapeutic device can then be placed in the target branch vessel.
Alternatively, if the tips are not to be bound, a positioning guide member can be introduced through the positioning guide member lumen. In this case, typically the positioning guide member will be advanced until the tip is just proximal to the exit port of the secondary catheter member. The placement catheter is introduced over the tracking guide wire through the tracking guide wire lumen, and the distal end of the positioning guide member is then advanced through the positioning guide member lumen and through the secondary catheter member into the main branch vessel. The placement catheter is advanced distally with a tip in each vessel of the bifurcation until the elongated angle member engages the vessel carina between the branch vessels, and the therapeutic device can then be placed in the target branch vessel as is illustrated in FIG. 5.
As used herein, the terms xe2x80x9cproximalxe2x80x9d and xe2x80x9cproximal directionxe2x80x9d when used with respect to the invention are intended to mean moving away from or out of the patient, and the terms xe2x80x9cdistalxe2x80x9d and xe2x80x9cdistal directionxe2x80x9d when used with respect to the invention are intended to mean moving toward or into the patient. These definitions will apply with reference to apparatus, such as catheters, guide wires, and stents. When used with reference to body lumens, such as blood vessels, the terms xe2x80x9cproximalxe2x80x9d and xe2x80x9cproximal directionxe2x80x9d are intended to mean closer to the aorta; the terms xe2x80x9cdistalxe2x80x9d and xe2x80x9cdistal directionxe2x80x9d are intended to mean farther from the aorta; and with respect to a bifurcated body lumen in general, the terms xe2x80x9cdistalxe2x80x9d and xe2x80x9cdistal directionxe2x80x9d are intended to mean in the direction in which the branching from the parent lumen to the branched lumens occurs.
These and other aspects and advantages of the invention will become apparent from the following detailed description and the accompanying drawings, which illustrate by way of example the features of the invention.